Floor systems, particularly hardwood floor systems, are commonly supported by sleepers. Sleepers are elongated nailing members, often of wood, laid end to end in parallel rows to form a subfloor layer for supporting a layer of floorboards secured thereabove. The sleepers may be relatively narrow and spaced from each other, or the sleepers may be relatively broad with edges of adjacent rows in abutting relationship. If desired, one or more subfloor layers may be used between the wear layer and the sleepers. The sleepers support the other floor components above a base.
One recognized advantage of supporting a floor system with sleepers relates to moisture susceptibility. The components of most floor systems are made of wood. Humidity changes from season to season cause wooden components of floor systems, and particularly an upper layer of floorboards, to expand with moisture intake and contract with moisture expulsion. Because sleepers support these other components above the base, the sleepers limit moisture transfer between the base and these other components. Moreover, if the sleepers are narrow and spaced away from each other, the free space between the supported components and the base enables air to circulate air therebetween to minimize moisture transfer.
Because moisture-caused expansion and contraction of floor system components may result in buckling, it is desirable to securely anchor the floor system, particularly the sleepers, to the base below. Anchoring of the sleepers provides an acceptable level of dimensional stability for the floor system, compared to a floor system wherein the sleepers are unanchored.
It is also desirable for hardwood floor systems to provide a degree of resilience. In the context of this application, resilience generally means the ability of a floor system to absorb shock upon impact and to deflect downwardly upon impact. Particularly for hardwood floors used in athletic contests, the resilience of the floor system may play a major role in reducing the incidence of athletic injury. In short, if a floor provides some degree of give, the stress placed upon the musculoskeletal structure of the athlete is reduced.
It is common practice to provide resiliency for a floor system by locating compressible pads below the sleepers. The compressibility of the pad enables the sleepers and the floorboards thereabove to deflect downwardly. The amount of downward deflection and the shock absorption of the floor system will depend upon a number of factors, including the shape and composition of the pads.
Recent studies indicate that, while resiliency is important to the reduction of susceptibility to athletic injury, uniformity in resiliency is also critical. Thus, it is desirable to provide a floor system with a high degree of resiliency which is also uniform throughout its surface area.
Unfortunately, it has proved difficult to achieve dimensional stability, optimum resiliency and uniformity in resiliency for hardwood floors supported by sleepers. The enhancing of one of these two features commonly adversely affects the other. For instance, when sleepers are supported above the base by a plurality of compressible pads and the sleepers are fastened to the base, direct fastening of the sleeper produces some initial compression, or precompression of the pads which is greater than the normal compression due to gravity from the components located thereabove. The pads remain compressed to this state throughout the life of the floor, even when the floor is unloaded.
Because of this already compressed state, the capability of the pads for further deflection is inhibited, and the overall resiliency of the floor system is greatly reduced. Another disadvantage results from this excess precompression. Because an excessive percentage of the compressibility is "used up", the floor has a higher chance of "bottoming out" or deflecting to its maximum, upon impact from above. This occurs when the pads compress maximally to a state where the floorboards deflect into contact with the rigid fasteners. On the other hand, if the floor system is free-floating, i.e. the sleepers are not anchored securely to the base, the entire floor system may be dimensionally unstable.
While some commercially available floor systems have achieved some degree of success in addressing one or more of these concerns, such floor systems tend to have a relatively high cost due to an increase in the number or complexity of structural components required for achieving these features and the increased costs associated with shipping and installing these components. As a result, the benefits of these floor systems have been limited unnecessarily to a relatively low number of users.
It is an objective of this invention to achieve optimum dimensional stability and optimum resiliency and uniformity of resiliency for a hardwood floor system.
It is another objective of this invention to substantially improve resiliency and dimensional stability for a relatively low cost hardwood floor system.
It is still another objective of this invention to enhance the dimensional stability of a hardwood floor system without producing a corresponding loss of resiliency, or loss in uniformity of resiliency.
The objectives of this invention are achieved by a sleeper construction which utilizes an attachment or nailing member supported by compressible pads above a base and a fastening arrangement which secures the attachment members directly to the base without interacting with the pads. This fastening arrangement enables the attachment members to deflect downwardly upon impact to upper floor layers but restricts upward raising of the attachment members beyond the initial static position of the pads. More importantly, this fastening arrangement enables the attachment members to be anchored to the base in a manner which does not precompress the pads when the floor system is unloaded. Thus, this anchored/resilient sleeper provides optimum dimensional stability and resiliency.
Because the manner of anchoring the attachment members does not precompress the pads or hold them in a precompressed state, i.e. beyond the normal weight bearing compression due to components located thereabove, an even distribution of the compressible pads along the attachment members will assure a uniformly resilient, yet firmly anchored, floor system.
Additionally, because of its simplicity and relatively few number of parts, the embodiments of this invention provide anchoring, resiliency and uniformity in resiliency for a sleeper-type floor system at a low cost. Fabrication and installation of the attachment members is also simplified. Finally, because the fastening arrangement provides secured anchoring, the lengths of the attachment members may be increased if narrow, spaced attachment members are used. As a result, less waste is produced and shipping, handling and installation costs are reduced.
According to one preferred embodiment of the invention, a fastener construction is utilized which may be of one, two or three piece construction. With this embodiment, each attachment or nailing member has at least one vertical bore extending from an upper surface to a lower surface thereof. At least one compressible pad is secured to the lower surface. The vertical bore includes an enlarged-diameter upper portion and a reduced-diameter lower portion.
The three piece construction includes a sleeve, a washer and the fastener. The sleeve resides within the lower, reduced-diameter portion, with the bottom edge of the sleeve contacting the base and the top edge of the sleeve residing adjacent the upper portion of the bore. The washer resides on top of the sleeve, in alignment therewith, and the fastener extends therethrough.
According to a second variation of this first preferred embodiment of the invention, the sleeve includes an upper flange, and no washer is necessary. For both variations, a fastener extends downwardly through the flange, through the sleeve and into the base. An enlarged head at the top of the fastening pin engages and holds the washer or the flange against the bottom surface of the upper portion of the bore.
According to a third variation of the invention, the fastener arrangement may comprise a single anchor pin with an enlarged top end, or head, having a diameter greater than the bore lower portion but less than the bore upper portion, a bottom end to be driven into the base and a depth stop located between the top and bottom ends. The depth stop feature may not be necessary for some installations. The vertical distance between the depth stop and the top end is approximately equal to the combined vertical dimension of the attachment member and the pad.
For all three variations, because the outer diameter of the sleeve or fastener is less than the diameter of the reduced-diameter lower portion of the bore, upon impact from above the attachment member may deflect downwardly in an unimpeded manner. The combined vertical dimension of the: 1) sleeve and the washer (first variation); 2) the sleeve with flange (second variation); or 3) the non-embedded portion of the fastener (third variation), is equal to the combined vertical dimension of the pad and the lower portion of the bores. Thus, for all three variations, the structure provides a solid line of rigid material between its top end and the base, so that downward driving forces applied via the fastening pin do not precompress the pads.
Preferably, the vertical dimension between the top of the fastening pin and the upper surface of the nailing member is greater than the maximum compression of the pads. This ensures that, upon downward deflection of the nailing members, the fastening pin will not project above the upper surface of the nailing member to contact an above-subfloor or floorboard layer.
To produce this structure, the nailing members are cut to a desired length and to a desired width, which may be relatively narrow or relatively broad, depending upon the type of floor system. The bores are then cut vertically through the nailing members from the upper surface to the lower surface. Thereafter, the compressible pads are secured to the lower surface of the nailing member. The number of pads and bores will depend upon the lengths and widths of the nailing members and the desired orientation. With the bores cut and the pads secured, the sleepers are ready for shipping to the job site. Alternately, if desired, these two latter steps may be performed at the job site.
To install this structure, multiple nailing members are laid end to end in parallel rows, with the spacing between the rows dependent upon the widths of the nailing members, and also dependent on whether any open space is necessary between adjacent rows. The pads support the members above the base. If the nailing members are panel-type, there will be some spacing between adjacent rows. If desired, every other nailing member in each row may be offset laterally. If using the first or second variation, the sleeves and washers, or sleeves with flanges, are then placed within the bores. Subsequently, fastening pins are driven through the sleeves, or through the sleeve and washer, and then into the base below. For the third variation, the fasteners are driven into the base without prior placement of the sleeves and/or washers.
Alternatively, holes may initially drilled into the base, as by extending a drill bit through the bores, and then the fastening pins may be driven into the drilled holes. This eliminates the possibility of cracking of the base, which may occur upon impact when pre-drilled holes are not used. When fully extended, the head ends of the fastening pins engage either the top surfaces of the washers, the top surfaces of the flanges or the nailing member itself, depending upon which construction is used. In this manner, the heads of the fastening pins hold the bottoms of the counterbores in the nailing members.
Because the sleeve and washer, the sleeve with the flange, or the fastener alone, does not compress vertically during installation, the fastener structure bears all the vertical force during installation. As a result, driving of the fasteners into the base does not vertically compress the pads. Moreover, after installation, when the floor system is unloaded, the pads are not held in a compressed state, i.e. beyond the compression due to normal weight bearing of components thereabove. Accordingly, after installation, the compressible pads retain their maximum compressive capability, thereby providing optimum resiliency potential throughout the floor system.
With the single piece anchor pin construction, after drilling the holes in the base, the anchor pins are extended through the bores and driven directly into the holes in the base to achieve secured engagement therein. The depth stops limit downward movement of the anchor pins to position the top ends thereof at a predetermined vertical distance above the base, this predetermined distance being equal to the combined vertical dimension of the pads and the lower portions of the bores of the attachment members.
The upper flooring layers are then secured to the tops of the nailing members. According to one preferred construction, at least one subfloor of panels is secured to the relatively narrow nailing members, and then tongue-and-groove maple floorboards are secured to the uppermost layer of panels. Because of the combination of anchored and resilient nailing members, along with the one or more layers of panels, this particular floor construction provides resiliency with a high degree of uniformity throughout its entire surface area. As indicated previously, recent studies suggest that, in addition to resiliency, uniformity of resiliency also plays a critical role in reducing athletic injury on athletic floor systems and enhancing performance.
Alternatively, the floorboards may be secured directly to the nailing members. This embodiment may be desirable if only one subfloor layer of wide, panel-type nailing members is utilized, or even if one layer of relatively narrow, spaced rows of attachment members is used. As still another alternative, if desired, the upper flooring layer may comprise one or more wood or non-wooden layers, depending upon the primary commercial use of the floor system.
Because of the relatively few number of parts and simple construction, this inventive structure provides conventional stability, resiliency and uniformity in resiliency for a hardwood floor system at a relatively low cost, compared to prior anchored and resilient sleeper-type floor systems.
Additionally, with the third variation of the invention, an already installed free floating floor or an anchored floor supported on resilient pads may be easily retrofitted or repaired to securely anchor the attachment members to the base in a manner which accomodates downward deflection but no vertical raising.
The invention contemplates several additional features applicable to all of the embodiments, such as "slicing" the attachment members horizontally to use a stacked or two-component attachment member. This eliminates the need to mill a two diameter bore, and it also provides an additional degree of versatility in constructing and arranging the subfloor.